Always pray mage....It's best to have quick prayers set because when shoots purple fireball it will disable prayers.
Always dodge flaming fireball/ move 2 spaces over that he spits in air, if not it will one shot you or x1 space over will do half damage to health.
I prefer to always walk here for acid pool and walking/being close to him makes flaming fire ball fall slowly another reason I personally prefer melee on this boss.
You don't have to spec the boss with claws can use dwh to drop defense or another other spec weapon just for damage.
Like all dragons he is weak to stab and can use any stab weapon. Also when he freezes you he's untouchable until kill the little spawn, can negate damage by killing him before he touches you as I do in this video, or just tank the damage witch is random but can max up to 30. Hope this video provides some help to those in need